mmc: core: add DT bindings for eMMC HS400 1.8/1.2V

Provide the option to configure these speed modes per host,
for those host driver's that can't distinguish this in runtime.
Specially, if host can support HS400, it means that host can also
support HS200.

Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>

Documentation/devicetree/bindings/mmc/mmc.txt

@@ -38,6 +38,8 @@ Optional properties:
 - mmc-highspeed-ddr-1_2v: eMMC high-speed DDR mode(1.2V I/O) is supported
 - mmc-hs200-1_8v: eMMC HS200 mode(1.8V I/O) is supported
 - mmc-hs200-1_2v: eMMC HS200 mode(1.2V I/O) is supported
+- mmc-hs400-1_8v: eMMC HS400 mode(1.8V I/O) is supported
+- mmc-hs400-1_2v: eMMC HS400 mode(1.2V I/O) is supported
 
 *NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line
 polarity properties, we have to fix the meaning of the "normal" and "inverted"

drivers/mmc/core/host.c

@@ -447,6 +447,10 @@ int mmc_of_parse(struct mmc_host *host)
 		host->caps2 |= MMC_CAP2_HS200_1_8V_SDR;
 	if (of_find_property(np, "mmc-hs200-1_2v", &len))
 		host->caps2 |= MMC_CAP2_HS200_1_2V_SDR;
+	if (of_find_property(np, "mmc-hs400-1_8v", &len))
+		host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
+	if (of_find_property(np, "mmc-hs400-1_2v", &len))
+		host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
 
 	return 0;